Machine for manufacture of prestressed concrete conduit



P. W. PALMER May 4, 1965 MACHINE FOR MANUFACTURE OF PRESTRESSED CONCRETE CONDUIT Filed sept. 2'?

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ATTORNEYS 3 Sheets-Sheet l um. Ulllllll mr P. W. PALMER May 4, 1965 MACHINE FOR MANUFACTURE OF PRESTRESSED CONCRETE CONDUIT 3 Sheets-Sheet 2 Filed Sept. 27 1962 INVENTOR PEQCY W PAM. 45

BY ML2( MFM/A ATTO/@NE )(5 May 4, 1965 P. w. PALMER 3,181,222

MACHINE FOR MANUFACTURE OF PRESTRESSED CONCRETE CONDUIT Filed Sept. 27, 1962 3 Sheets-Sheet 3 gfx INVENTOR.

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ArraEA/Ev United States Patent O 3,181,222 MACHINE FOR MANUFACTURE OF PRE- STRESSED CONCRETE CONDUIT Percy W. Palmer, 502 Washington St., Edgerton, Wis. Filed Sept. 27, 1962, Ser. No. 226,673 3 Claims. (Cl. 25-41) This invention relates to improvements in machines for molding a tubular member from concrete reinforced by pre-stressed metal reinforcement, and particularly to a machine for forming multi-duct conduit of concrete with such reinforcement.

The use of pre-stressed metal reinforcement in precast concrete beams, so-called planks and the like remarkably increases the strength of such products as compared to use of the same reinforcement in unstressed condition. Applying the above knowledge to the manufacture of tubular products, such as multiple duct conduit of concrete for electric lines and the like, is desirable but economically practical only if means are devised to manufacture the conduit as a multiple of the length which can be most practically handled in the field for this purpose. The present invention provides a machine by which concrete multi-duct conduit can be made under the above conditionsrand which will otherwise meet the requirements for a practical and economic machine for casting pre-stressed concrete multi-duct conduit,

Generally, the present machine embodies a base which serves as a stationary side of a four-sided mold and 'on which a first bulkhead closes one end of the mold. The base serves also as a track for a carriage for three movable sides of the mold and supports a second bulkhead for the other end of the mold and cores which are progressively withdrawn from the concrete to form the conduit ducts. One side of the mold is resiliently mounted so that high pressure compaction of the concrete will not affect the mold and the full stroke of a compacting means may be exerted on an end of the concrete in the mold. Vibration may be exerted on various parts of the machine and vibrating tampers are provided for securing vibration across the entire cross section of the concrete within the mold, both close to the mold sides and between the mold cores to insure that the concrete will completely fill the mold. Other vibrating means are mounted on various machine parts such as the support for the duct cores, for working the concrete in the mold. The vibrators may operate continuously or may be part of an automatic cycle in which various parts are controlled in sequence. Thus the vibrating tampers may be at a standstill when not working in the concrete. It is preferable to feed and vibrate the concrete simultaneously until a given length of the mold has been filled, whereupon concrete feeding is stopped and the vibrating tampers are raised from the concrete. Thereafter pressure acts endwise on the concrete to aid in filling the mold and the reaction from such pressure moves the carriage to another concrete feeding position. The electric motors feeding the concrete and positioning the vibrating tampers operate in sequence with the motor producing endwise pressure on the concrete and the cycle is made automatic and is timed to assure completion of each step before another step begins.

In the drawings:

FIG. l is a perspective view of a reinforced concrete multiple duct conduit, which is the product of the present invention.

FIG. 2 is a side elevation of an installation for manufactoring said conduit.

FIG. 3 is a side elevation of the carriage of the machine for molding the conduit, with parts omitted or broken away to show internal structure of the carriage.

llg Patented May 4, 1965 FIG. 4 is a perspective view of a first bulkhead forming one end wall of the mold in its initial position.

FIG. 5 is a partial end View of movable side plates of the mold and its carriage on the base.

FIG. 6 is a cross-section on the line 6-6 of FIG. 3.

FIG. 7 is a top plan view of the carriage shown in FIG. 3.

FIG. 8 is a horizontal section on the line 8 3 of FIG. 6 and shows the means for positioning the reinforcement and cores and for pressing endwise on the concrete.

FIG. `9 is an enlarged side view of a portion of the carriage and FIG. 10 is a cross-section on the line 10-10 of FIG. 9.

Referring by numerals to the drawings, lthe product is a conduit 15 with a number of ducts 16 molded in concrete and reinforced with pre-stressed steel cables 17, the cables being shown as running longitudinally of the conduit adjacent each corner thereof. However, it will be understood that the cables 17 may also be placed elsewhere in the body of the conduit. The cables in the present installation are pre-stressed to a total of 19,00() pounds tension but can of course be stressed to any value found to be particularly useful in making reinforced conduit.

A base Ztl which may be in the form of steel plate of substantially box section, supports and forms a track for a carriage of the machine and one surface of the base is so treated as to be substantially non-adherent to concrete so that conduit cast thereon may be readily released from the base. The base is several times the desired length of one conduit, the base being 320 feet in the present installation so that a finished conduit can be cut into a number of 20 or 40 foot lengths or otherwise as desired by a user. At the two ends of the base 20, are placed heavy anchorages including pillars 21 embedded in concrete foundations 22 for holding the cables 17 under tension. The ends of the cables are anchored in known gripping means 23 engaging the pillars to hold the cables in spaced relation as shown in the conduit and while under tension. A first bulkhead 24 forming a part of a mold, is threaded on the cables and has grippers 25 thereon to engage the cables and to position the bulkhead on the base Ztl so that the bulkhead provides an end plate against which the concrete is pressed by the movable portion of the machine.

The carriage of the molding machine (see FIG. 5) comprises vertical frame members 29 joined at the lower ends by axles Ell on which pairs of flanged wheels 31 are mounted to run along the top of the base Ztl with the wheel flanges running along the base sides. The upper ends of vertical frame members 29 are joined by horizontal cross members 32 and longitudinal members 33 to provide a heavy girder-like frame structure. Mold side plates 34 are supported in the frame 29-33 to run in edgewise sliding contact on the base 20. A mold top plate 35 is supported on adjustable rods 36 under the pressure of springs 37 to provide a yielding pressure on the concrete and to allow variation in position of the top plate relative to the side plates. One or more vibrators may be mounted upon the mold top plate, if desired. A movable and second bulkhead 40 is carried by the frame and has apertures therethrough (which may be plugged if not in use) to pass cables 17 and has apertures therethrough to space and support a plurality of cores 41 to produce the conduit ducts 16, such cores preferably being relatively thin wall tubing suitably cross braced. The bulkhead ilb is mounted (see FIG. 8) on means for moving the same relative to the mold and cores as will be described.

The cores 41 are mounted at one end in and extend from a support member (see FIGS. 6 and 8) comprising side plates 42 and cross plates 43, the side plates being adjustably attached by bolts 44 to the frame vertical members 29 and spaced from the frame by resilient pads 45. Push rods 56 extend through the cross plates 43 of the core support and are attached to the bulkhead 40 and to a piston rod 51 in a hydraulic cylinder 52 by which the bulkhead 40 may be moved endwise relatively to the mold Sides and top, 20, 34 and 3S for compacting the concrete. Pressure for the ram 51, 52 is provided by an electric motor 53 and pump 54 as is usual in hydraulic systems, motor 53 being controlled in sequence with other electric motors of the carriage, as will be described. The stroke of ram 51, 52 is preferably of the order of inches. A known electrically driven vibrator 55 is mounted on the core support 42-45 and is preferably operated at approximately 10,000 cycles per minute.

Mold top plate 35 does not extend the full length of the mold side plates 34 so that space is provided through which vibrating tamper mechanism may act across the entire section of the concrete in the mold. Such vibrating tamper (see FIG. 3, 9 and 10) comprises a frame of corner posts 58 fixed on carriage members 33 and joined at their upper end by a top plate 59 or the like. A platform 60 with tubular legs 61 slides up and down on the posts 58 and such platform and legs carry plural vibrating tamper plates 62 extending downwardly from the elevator platform 60-61 to pass between the core tubes 41 into the concrete and to the bottom of the mold. The elevator platform 60-61 and the plates 62 are vibrated by an electric type of vibrator 63 such as indicated above.

Vertical movement of the tamper 60-62 is obtained by suitable lifting means, the lift shown in the present instance including a pedestal 68 on which is mounted a pivot shaft 69 for arms 70 pivotally connected by links 71 with elevator 60-61. A crank shaft 72 is also mounted on the pedestal 68 and is driven by motor 74 mounted on bracket 75. Crank shaft 72 is connected with arms 70 by rods 76 so that swinging the arms on the pivot axle 69 raises the tamper plates 62 out of or presses them down through the concrete in the mold. The vibrator 63 causes plates 62 to work the concrete, particularly adjacent the cores and reinforcement, so that no voids remain therein.

Concrete from any source, indicated at 79 in FIG. 1, is delivered to the machine by way of a hopper 80 from which the concrete fiows through a gate 81 onto a belt conveyor S2, driven by a motor 83. The conveyor 82 dumps the concrete into the opening between the mold top plate 35 and the bulkhead 40 which is movable relative to the entire mold. The tamper motor 74 and the feed conveyor motor 83 are preferably operated simultaneously so that concrete is vibrated as it is being placed as well as by movement of the plates 62 across the entire mold.

FIG. 2 shows the fixed bulkhead 24 in position with a molded portion of conduit extending toward the right from the first bulkhead 24 and into the machine carriage. FIG. 3 shows the position of the machine parts while concrete is being supplied to the mold and is being vibrated by the tamper, the concrete being omitted from the mold to show the cables and cores and the tamper plates therein and FIG. 9 shows the position of the machine parts when the tamper plates 62 are elevated to allow the bulkhead 40 to be moved within the mold for pressing endwise on the concrete in the mold.

In operation, the reinforcing cables 17 are fixed by grippers 23 to the anchorage 21-23 and are threaded through cable grippers on first bulkhead 24 and through second bulkhead 40, core support 42-45 and anchorage 21a-23a. Tension is put on the cables 17 and the cable grippers 25 of first bulkhead 24 are locked to the cables at a desired location on base 20 dependent on the total length of product to be made. The machine carriage is now moved to bring the free end of the cores 4l against the bulkhead 24. The mold top plate 35 terminates a considerable distance to the left of the movable bulkhead 40 for reception of concrete in the mold. Concrete is now simultaneously delivered to the mold and vibrated by the tamper 60-62 and any other vibrators on other parts of the machine so that the concrete substantially fills the mold from the bulkhead 24 to substantially the right hand end of the mold. The tamper plates 62 are now raised and the bulkhead 40 is moved toward the left by hydraulic means 49-54 to the position shown in FIG. 9, to press on the concrete endwise. During the above action the concrete has been progressively setting from the first bulkhead 24 toward the right and the length of the carriage is such that the concrete is firm enough to retain its form adjacent the first bulkhead if both the mold and the cores are withdrawn from such set portion of the concrete when the mold is filled.

The reaction from pressure on the concrete moves the carriage toward the right as a whole, which moves the ram i1-52, core support 42-43 and cores 41, and bulkhead 40 bodily toward the right. The ram is now retracted so that bulkhead 40 is moved farther toward the right and the above movements draw the mold side and top plates and the cores away from the rst bulkhead 24. Such withdrawal is however relatively easy because the various vibrators have produced a film of water adjacent the mold plates and the water permits movement of the mold parts relative to the concrete and aids in smoothing the surfaces of the concrete.

When a space is again obtained in the mold below the tamper plates 62, such plates are put into vibration and concrete is again delivered to the mold. It is preferable that plates 62 move up and down while vibration continues so that the entire cross section of the concrete in the mold is subjected to the tampers a number of times as a particular mold length of the conduit is being filled. After the mold is filled, the tampers 62 are kept raised until the bulkhead 40 is moved toward the left to press the concrete, whereupon the bulkhead and the carriage as a whole are again drawn to the right.

It will be seen that the carriage includes an electric feeding motor 83, tamper motor 74 and ram motor 53 and electric vibrators 55 and 63 and any other vibrators desired. Feeding and tampering are done simultaneously and the tamper may continue to operate after feeding is ended and all other vibrators are also operated during feeding and tamping. Ram motor 53 is not energized until feeding is stopped and the tamping plates are elevated. At such time all the vibrators may be operated to combine vibration and ram pressure on the concrete or the vibrators may be stopped to apply pressure only, dependent upon the size and kind of product being made because experience shows that different operations are desirable for different products or at different times. The sequence of operations of the carriage motors 53, 74 and 83 does not change and is therefore preferably controlled automatically by the usual adjustable timer switch. However, except when a large amount of a particular product is to be made in one run, the vibrator action should be different from product to product, for different products and at different times in the casting cycle. Hence the vibrators are usually controlled manually to allow various combinations of Vibrator action.

Aside from the base, the anchorages and the first bulkhead, all other machine parts are included in the carriage. A heavy and rigid frame on wheels carries various subassemblies including mold parts with cores, concrete feeding means, elevating tamping mechanisms and means for pressing on the concrete in the mold. The sequence of motors for operating the above sub-assemblies is fixed, but the length of the cycle is adjustable. Vibrators are applied to various sub-assemblies and are used during the pouring of the concrete and in various combinations and at various times, in combination with the pressing means. Accordingly both the machine structure and the present method of operation are believed necessary to successfully manufacture various prestressed reinforced concrete products of tubular form.

l claim:

1. in a machine for casting concrete tubular products having prestressed metal reinforcement therein, a base substantially non-adherent to concrete and forming part of a mold for casting the product, and an anchorage at each end of the base for holding the reinforcement in prestressed condition, a lirst bulkhead positioned on the base and initially forming one end of the mold, a carriage rnovable on and along the base as a track and comprising a frame, plates coacting with the base in forming the four sides of a inold and providing an opening for access of concrete to the mold, a second bulkhead on the carriage within the mold and rnovable relative thereto for forming an end for the mold, the two bulkheads having apertures for passing the reinforcement therethrough to position the reinforcement relative to the four sides of the rnold, means on the carriage for moving the second bulkhead longitudinally of the mold and relative thereto to press on the concrete in the mold, a frame resiliently mounted on the carriage, spaced cores mounted .at one end on the frame to overhang from the trarne and having the free ends thereof extending into the mold through the second bulkhead, vibrating means mounted on the trarne for impressing vibration along the overhanging length of the cores, and means on the carriage for feeding concrete through the access opening into the mold at the end thereof receiving the second bulkhead.

2. The machine of claim 1 in which a tamper is mounted on the carriage and comprises plates movable through the mold access opening adjacent the mold sides and adjacent the cores and transversely of and into the mold to adjacent the base and out of the mold to a position above (5:5 the second bulkhead, and a vibrator mounted on and mow ing with the plates for vibrating the same in their movement across the cross section of the mold.

3. The machine of claim 1 in which a vertically movable platform is mounted over the access opening into the rnold and has plates extending therefrom for movement transversely of and into and out of the mold alongside each of the cores and the mold side plates, and vibrating rneans is mounted on the platform for vibrating all of the plates.

llelerences @Cited hy the Examiner UNITED STATES PATENTS 272,410 2/83 Campbell 25132 639,858 12/99 Martin et al 25-32 1,920,716 8/33 Schafer 25-118 2,225,015 12/40 Lebelle 25-118 2,324,760 7/43 Brulotte 25-32 2,748,442 6/56 Butcher 25-32 2,938,255 5/60 Oakden 25-32 2,948,942 8/ 60 Gordon 25-32 2,969,576 1/61 Fuller 25-32 2,970,361 2/61 Brown 25-99 3,049,786 8/62 Jones 25-32 3,049,787 8/62 Hannan et al. 25-32 FOREIGN PATENTS 228,818 6/ 60 Australia.

OTHER REFERENCES Gessner: German application, 1,008,180, printed May 9, 1957, K180a49.

ROBERT F. WHITE, Prmary Exam incr. 

1. IN A MACHINE FOR CASTING CONCRETE TUBULAR PRODUCTS HAVING A PRESTRESSED METAL REINFORCEMENT THEREIN, A BASE SUBSTANTIALLY NON-ADHERENT TO CONCRETE AND FORMING PART OF A MOLD FOR CASTING THE PRODUCT, AND AN ANCHORAGE AT EACH END OF THE BASE FOR HOLDING THE REINFORCEMENT IN PRESTRESSED CONDITION, A FIRST BULKHEAD POSITIONED ON THE BASE AND INITIALLY FORMING ONE END OF THE MOLD, A CARRIAGE MOVABLE ON AND ALONG THE BASE AS A TRACK AND COMPRISING A FRAME, PLATES COACTING WITH THE BASE IN FORMING THE FOUR SIDES OF A MOLD AND PROVIDING AN OPENING FOR ACCESS OF CONCRETE TO THE MOLD, A SECOND BULKHEAD ON THE CARRIAGE WITHIN THE MOLD AND MOVABLE RELATIVE THERETO FOR FORMING AN END FOR THE MOLD, THE TWO BULKHEADS HAVING OPERTURES FOR PASSING THE REINFORCEMENT THERETHROUGH TO POSITION THE REINFORCEMENT RELATIVE TO THE FOUR SIDES OF THE MOLD, MEANS ON THE CARRIAGE FOR MOVING THE SECOND BULKHEAD LONGITUDINALLY OF THE MOLD AND RELATIVE THERETO TO PRESS ON THE CONCRETE IN THE MOLD, A FRAME RESILIENTLY MOUNTED ON THE CARRIAGE, SPACED CORES MOUNTED AT ONE END ON THE FRAME TO OVERHANG FROM THE FRAME AND HAVING THE FREE ENDS THEREOF EXTENDING INTO THE MOLD THROUGH THE SECOND BULKHEAD, VIBRATING MEANS MOUNTED ON THE FRAME FOR IMPRESSING VIBRATION ALONG THE OVERHANGING LENGTH OF THE CORES, AND MEANS ON THE CARRIAGE FOR FEEDING CONCRETE THROUGH THE ACCESS OPENING INTO THE MOLD AT THE END THEREOF RECEIVING THE SECOND BULKHEAD. 